SafeSol Ltd and Huwa-San
SafeSol Ltd introduced Huwa-San into the UK legionella control market in 2004 and have used it since that time. The chemical has found steady acceptance since that time as
- a competitor to chlorine for one-off water disinfections and
- a competitor to chlorine dioxide as a continuous dose chemical.
Like all innovative treatments Huwa-San has been opposed by traditionalists, by companies selling competitor disinfectants, and by companies using other me too silver stabilised hydrogen peroxides.
Chlorine and Biofilm: The Theory
Why Does Chlorine remain the disinfectant of choice?
Despite this chlorine (generally based on sodium hypochlorite solution) is still the disinfectant of choice for domestic water systems, most cooling towers, swimming pools, spas, and hot tubs. These are all situations where biofilms form. Yet a Scottish NHS hospital engineer, almost 30 years ago, knew something then that many people today have still to learn
In systems with no or little biofilm, chlorination will probably be successful. The problem lies if there is a legionella based biofilm in a system. Chlorination will only attack the outer layers of the biofilm. It takes a number of days for the biofilm to recover. Therefore immediately following a chlorination, the sluggish biofilm, will not be sloughing or sending bacteria into the water. This results in low TVC levels (Total Viable Count- Levels of general bacteria) when samples are taken after chlorination. A few days later as the biofilm regenerates legionella bacteria will start to appear in the water again. Therefore the system can appear clean whereas in reality there is a legionella issue.
Bob Wilson’s next blog looks at chlorine dioxide as a biofilm remover.